Tens of thousands of striking rail workers, public sector staff and students have rallied across France against President Emmanuel Macron.

Demonstrators chanted and carried anti-Macron banners on Thursday in Paris and other cities such as Lyon and Marseille, but the scale of the protests appeared below expectations.

About 15,000 rallied in Paris, according to a count by crowd consultancy, Occurrence, while police estimated the number at 11,500. Hard-left CGT union, the main organiser, put the crowd at 50,000.

"We're here for public services. We're ready to continue the whole summer, even into September and October," Helene Tricre, a 25-year-old ticket inspector working for the SNCF railway, told AFP news agency at the Paris rally.

The peaceful march was marred by occasional clashes between police and far-left groups, many of them hooded and masked, who were seen smashing shop windows.

Rail workers were on their fourth wave of stoppages this month [Benoit Tessier/Reuters]

Rail workers were also carrying out their fourth wave of stoppages this month, although the number of strikers was down sharply from the beginning of April.

Only one in three high-speed TGV trains was running, but this was higher than three weeks ago when only one in eight ran.

Staff at the debt-laden SNCF, a bastion of hard-left trade unionism, are striking for two days out of every five in protest against plans by Macron to remove job-for-life guarantees and pension privileges for new recruits.

The CGT union had called for various groups angered by Macron's one-year presidency - students, public sector employees, pensioners, rail workers - to come together to resist the 40-year-old centrist.

The march in Paris was marred by occasional clashes between police and far-left groups [Reuters]

Some left-wingers are even hoping for a re-run of the huge May 1968 demonstrations by workers and students that shook France half a century ago.

But Macron has vowed to stand firm, claiming a solid mandate from his election last year in which he swept away the traditional parties that governed France for decades.

"I'm doing what I said I would," he said last week.

Opinion polls suggest France remains deeply divided about his leadership, despite a sharp fall in unemployment and a pick-up in investment thanks to his business-friendly approach since taking power.

An Elabe survey showed on Friday that 52 percent of respondents felt his election has proven "a bad thing".

Another survey, released on Wednesday, found 58 percent were unhappy with his presidency.